Evaporator

ABSTRACT

An evaporator comprises front and rear header portions, and U-shaped flat tubular portions arranged in parallel and each connected at opposite ends thereof to the header portions. Each of the header portions is provided with a partition for blocking a refrigerant flowing inside thereof and directing the refrigerant toward some of the flat tubular portions to thereby form a refrigerant channel comprising a plurality of paths each turned by the partition. The rear header portion of the final path is provided with a refrigerant dividing wall having refrigerant apertures for passing therethrough a portion of the refrigerant flowing in from the path immediately upstream from the final path, with the remaining portion of the refrigerant blocked by the wall and directed toward some of the flat tubular portions.

BACKGROUND OF THE INVENTION

The present invention relates to evaporators for use in air conditionersfor motor vehicles.

Evaporators for use in motor vehicle air conditioners and the like arealready known which comprise first and second header portions arrangedin parallel, and flat tubular portions arranged in parallel and eachconnected at opposite ends thereof to the header portions, each of theheader portions being provided with a partition for blocking arefrigerant flowing inside thereof and directing the refrigerant towardsome of the flat tubular portions to thereby form a refrigerant channelcomprising a first path, at least one intermediate path and a finalpath.

With the conventional evaporator described above, the number of paths,i.e., the number of blocking partitions, is altered to obtain optimallydivided flows of the refrigerant. With decreases in the width ofevaporators in recent years, however, the refrigerant passing aperturesare reduced in area, and the refrigerant is moved from path to path atan increased rate, impairing the division of the refrigerant in adownstream path (especially in the final path) and permitting therefrigerant to unevenly pass through the flat tubular portions providingthis path, with an increased amount of the refrigerant flowing throughthe flat tubular portion at the downstream extremity. This imposes alimitation on the improvement of the cooling ability.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an evaporator whereinthe division of the refrigerant into separate flows in a downstream pathis optimized by a method other than varying the number of paths so as togive high cooling ability to the evaporator.

The present invention provides an evaporator which comprises first andsecond header portions arranged in parallel, and flat tubular portionsarranged in parallel and each connected at opposite ends thereof to theheader portions, each of the header portions being provided with apartition for blocking a refrigerant flowing inside thereof anddirecting the refrigerant toward some of the flat tubular portions tothereby form a refrigerant channel comprising a first path, at least oneintermediate path and a final path, the evaporator being characterizedin that at least one of the header portions is provided with at leastone refrigerant dividing wall having at least one refrigerant aperturefor passing therethrough a portion of the refrigerant flowing from oneof the paths into the path downstream from said one path, with theremaining portion of the refrigerant blocked by the wall and directedtoward some of the flat tubular portions.

In the case where one refrigerant dividing wall is provided in the firstheader portion of the evaporator of the invention, the refrigerantflowing out from one path into the first header portion of the pathimmediately downstream from the former path partly passes through therefrigerant aperture of the dividing wall to reach the downstream partof the first header portion of the downstream path and thereafter flowsthrough the flat tubular portions in communication with the downstreampart into the downstream part of the second header portion of thedownstream path. On the other hand, the portion of the refrigerantblocked by the dividing wall flows through the flat tubular portions inthe upstream part of the downstream path into the upstream part of thesecond header portion of the downstream path. The portions of therefrigerant divided by the wall join together inside the second headerportion, and the combined refrigerant flows out of the second headerportion into the path which is positioned further downstream.Accordingly, a greater quantity of refrigerant flows through the flattubular portions in the upstream part of the downstream path than whenthe evaporator has no refrigerant dividing wall, consequently giving auniform distribution of refrigerant temperatures throughout the entireevaporator to result in improved cooling ability. The same result isachieved in the case where one refrigerant dividing wall is provided inthe second header portion and in the case where one refrigerant dividingwall is provided in each of the header portions. Thus, the evaporatorexhibits a uniform distribution of refrigerant temperatures in itsentirety and improved cooling ability unlike evaporators having norefrigerant dividing wall.

Preferably, the final path causes the refrigerant to turn at a closedend of the first header portion and to flow out of an end of the secondheader portion which end has a refrigerant outlet, and the refrigerantdividing wall is singly provided in the first header portion of thefinal path. In this case, the refrigerant flowing into the first headerportion of the final path partly passes through the refrigerant apertureof the dividing wall to reach the downstream part of the first headerportion of the final path and thereafter flows through the flat tubularportions in communication with the downstream part into the downstreampart of the second header portion of the final path. On the other hand,the portion of the refrigerant blocked by the dividing wall flowsthrough the flat tubular portions in the upstream part of the final pathinto the upstream part of the second header portion of the final path.The portions of the refrigerant divided by the wall join together insidethe second header portion, and the combined refrigerant flows out of therefrigerant outlet of the second header portion. This ensures a uniformdistribution of refrigerant temperatures in the final path which is verylikely to impair the division of the refrigerant into separate flows,effectively attaining an improvement in the cooling ability.

Preferably, the refrigerant dividing wall has one to six refrigerantapertures. If the number of apertures is greater than six, the wallrequires much labor for machining, while a uniform distribution ofrefrigerant temperatures will not be achieved effectively.

Preferably, the refrigerant apertures are arranged in a plurality ofpairs, and each pair of refrigerant apertures are positionedsymmetrically. This arrangement obviates occurrence of an uneven flowinside the header portion, consequently eliminating the disadvantageresulting from the provision of the refrigerant apertures.

The refrigerant apertures are circular and have a diameter preferably of2.5 to 4.0 mm.

More preferably, the diameter of the refrigerant apertures is 3.0 to 3.5mm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the appearance of an evaporatorembodying the invention;

FIG. 2 is a fragmentary view in horizontal section showing the interiorof header portions of the evaporator;

FIG. 3 is a perspective showing a refrigerant channel of the evaporator;

FIG. 4 is a perspective view showing a pair of standard intermediateplates constituting the evaporator;

FIG. 5 is a view in horizontal section of a flat tubular portion of theevaporator;

FIG. 6 is a perspective view of a rear header partitioning intermediateplate constituting the evaporator;

FIG. 7 is a perspective view of a front header partitioning intermediateplate constituting the evaporator;

FIG. 8 is a perspective view of a refrigerant dividing wall formingintermediate plate constituting the evaporator;

FIG. 9 is a perspective view of an end intermediate plate and a standardintermediate plate paired therewith, these plates constituting theevaporator; and

FIG. 10 is a perspective view showing another embodiment of therefrigerant dividing wall forming intermediate plate shown in FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the invention will be described with reference to thedrawings.

The terms "front," "rear," "left" and "right" are used based on FIG. 2;the upper side of the drawing will be referred to as the "rear," thelower side thereof as the "front," and the left-hand side and right-handside thereof as "left" and "right," respectively.

An evaporator 1 embodying the invention is made of aluminum (includingan aluminum alloy) and comprises U-shaped flat tubular portions 5arranged in parallel, and front and rear header portions 6, 7, theseportions being formed by fitting together intermediate plates 2, 3, 3A,3B, 3C as will be described later. Corrugated fins 4 are interposedbetween each pair of adjacent flat tubular portions 5. A side plate 8 isfitted to each of opposite outer sides of the assembly of intermediateplates 2, 3, 3A, 3B, 3C fitted together. Corrugated fins 4 are providedalso between the side plate 8 and the tubular portions 5 adjacentthereto. Connected to the right end of the rear header portion 7 is arefrigerant inlet pipe 10 having an inner pipe portion 10a. Arefrigerant outlet pipe 11 is joined to the right end of the frontheader portion 6.

With reference to FIG. 2, the intermediate plates 2, 3, 3A, 3B, 3C areend intermediate plates 2 arranged at the left and right ends of theevaporator 1, a rear header partitioning intermediate plate 3Apositioned at a distance of about 1/3 of the length of the evaporatorrightward from the left end, a front header partitioning intermediateplate 3B disposed at a distance of about 1/3 of the length leftward fromthe right end, a refrigerant dividing wall forming intermediate plate 3Cpositioned at a distance of about 1/6 of the length leftward from theright end, and the remaining plates, i.e., standard intermediate plates3. At each of the left and right ends of the evaporator 1, the standardintermediate plate 3 and the end intermediate plate 2 are paired. Thenumber of plates shown in FIG. 2 is less than actually for the sake ofconvenience. In actuality, the evaporator has, for example, 21 pairs ofplates in total: one of the seventh pair of plates from the left end mayserve as the rear header partitioning intermediate plate 3A, one of theseventh pair of plates from the right end may serve as the front headerpartitioning intermediate plate 3B, and one of the fourth pair of platesfrom the right end may serve as the refrigerant dividing wall formingintermediate plate 3C.

FIG. 4 shows one pair of standard intermediate plates 3. With referenceto this drawing, the intermediate plate 3 comprises a generally U-shapedflat tube forming recessed portion 21 including a front vertical portion21a, a rear vertical portion 21b and a horizontal portion 21interconnecting these portions 21a, 21b; and front and rear headerforming recessed portions 22, 23 integral with the upper ends of therespective front and rear vertical portions 21a, 21b and having agreater depth than the recessed portion 21. Two refrigerant apertures24, 25, each in the form of a circle elongated transversely of theevaporator, are formed in the standard plate 3, respectively in thebottom walls 22a, 23a of the header forming recessed portions 22, 23.The tube forming recessed portion 21 of the intermediate plate 3 iscentrally formed with a vertical long ridge 26 extending from the upperend of the recessed portion 21 to a position close to the lower endthereof for providing a U-shaped refrigerant channel. With theillustrated pair of standard plates 3 fitted to each other, the recessedportions 21 thereof provide one flat tubular portion 5. Inner finmembers 29 having parallel vertical passages are interposed between thebottom walls of front and rear vertical portions 21a, 21b of the tubeforming recessed portions 21 of the pair of intermediate plates 3,whereby vertical parallel passageways are formed in the flat tubularportion 5 as seen in FIG. 5. The bottom wall of horizontal portion 21cof the tube forming recessed portion 21 is provided with a quadrantprotrusion 27 for forming a semicircular arc turn portion for holdingthe front vertical portion of the flat tubular portion 5 incommunication with the rear vertical portion thereof, and generallytriangular protrusions 28 arranged at the front and rear sides of lowerpart of the horizontal portion 21c for reinforcing the correspondingcorners of the plate 3 and permitting the refrigerant to flow throughthe turn portion smoothly. A projecting edge 25a is formed by burring onthe peripheral part around the refrigerant aperture 25 of the rearheader forming recessed portion 23 of the plate 3 at left in FIG. 4. Aprojecting edge 24a is formed by burring on the peripheral part aroundthe refrigerant aperture 24 of the front header forming recessed portion22 of the plate 3 at right in FIG. 4 (see FIG. 2). These projectingedges 24a, 25a are fitted in the refrigerant apertures 24, 25 of theheader forming recessed portions 22, 23 adjacent thereto as seen in FIG.2, whereby the intermediate plates 3 concerned are reliably positionedin place relative to one another. The inner fin member 29 may bereplaced by a plurality of ridges formed on the bottom wall of each ofthe front and rear vertical portions 21a, 21b of the tube formingrecessed portion 21 so as to form straight small passageways in thetubular portion 5.

FIG. 6 shows the rear header partitioning intermediate plate 3A. Withreference to the drawing, the intermediate plate 3A has a front headerforming recessed portion 22 which is formed in its bottom wall 22a witha refrigerant aperture 24 generally in the form of a circle elongatedtransversely of the evaporator, and a rear header forming recessedportion 23 which is formed in its bottom wall 23a with a through hole 30having a diameter equal to the outside diameter of the inner pipeportion 10a of the refrigerant inlet pipe 10. With the left end of theinner pipe portion 10a inserted through the hole 30, the bottom wall 23aof the recessed portion 23 serves as a rear header partition 12. Thebottom wall edge defining the through hole 30 is burred so as to give anincreased area of contact with the pipe portion 10a. The intermediateplate 3A has the same construction as the standard intermediate plate 3with the exception of the above feature, and like parts are designatedby like reference numerals and will not be described repeatedly.

FIG. 7 shows the front header partitioning intermediate plate 3C. Withreference to the drawing, the intermediate plate 3B has a rear headerforming recessed portion 23 which is formed in its bottom wall 23a witha refrigerant aperture 25 generally in the form of a circle elongatedtransversely of the evaporator, and a front header forming recessedportion 22 which is formed with no refrigerant aperture in its bottomwall 22a. The bottom wall 22a having no aperture serves as a frontheader partition 13. The intermediate plate 3B has the same constructionas the standard intermediate plate 3 with the exception of the abovefeature, and like parts are designated by like reference numerals andwill not be described repeatedly.

FIG. 8 shows the refrigerant dividing wall forming intermediate plate3C. With reference to the drawing, the intermediate plate 3C has a frontheader forming recessed portion 22 which is formed in its bottom wall22a with a refrigerant aperture 24 generally in the form of a circleelongated transversely of the evaporator, and a rear header formingrecessed portion 23 which is formed in its bottom wall 23a with athrough hole 30 having a diameter equal to the outside diameter of theinner pipe portion 10a of the refrigerant inlet pipe 10 and with tworefrigerant apertures 31 respectively at the front and rear sides of thehole 30. These apertures 31 are small, so that when the inner pipeportion 10a is inserted through the hole 30, the refrigerant flowingrightward in the rear header portion 7 partly passes through theapertures 31 as indicated by solid arrows in FIG. 2, while the remainingportion of the refrigerant is blocked by the bottom plate 23a anddirected toward the U-shaped flat tubular portion 5 as indicated by anarrow of broken line. Thus the bottom wall 23a, having the apertures 31,of the rear header forming recessed portion 23 serves as a refrigerantdividing wall 14.

FIG. 9 shows the left end intermediate plate 2 and the standardintermediate plate 3 paired therewith. With reference to the drawing,the left end plate 2 has front and rear header forming recessed portions22, 23 which are formed in their bottom walls 22a, 23a with norefrigerant aperture. Two U-shaped reinforcing plates 15 are providedbetween, and fitted to, each of the left and right end intermediateplates 2 and the standard intermediate plate 3 paired therewith, each ofthe reinforcing plates 15 being fitted to the lower half of innerperiphery of peripheral wall of each recessed portion 22 (23). Thereinforcing plate 15 has a width equal to the depth of the recessedportion 22 (23) of the end plate 2 plus the depth of the recessedportion 22 (23) of the standard plate 3. The reinforcing plate 15 isformed with a plurality of refrigerant apertures 15a for holding theheader portion 6 (7) in communication with the flat tubular portion 5.In the case of the right end intermediate plate 2, the bottom wall 22aof the front header forming recessed portion 22 is formed with a throughhole serving as a refrigerant outlet 32 and having a diameter equal tothe outside diameter of the refrigerant outlet pipe 11, and the bottomwall 23a the rear header forming recessed portion 23 is formed with athrough hole 30 having a diameter equal to the outside diameter of innerpipe portion 10a of the refrigerant inlet pipe 10.

The intermediate plates 2, 3, 3A, 3B, 3C are arranged side by side andfittingly joined to one another, with their recessed portions 21, 22, 23facing toward opposite directions alternately, whereby the parallelU-shaped flat tubular portions 5 and the front and rear header portions6, 7 are formed. The front and rear header portions 6, 7 are formed withthe respective partitions 12,13 for blocking the refrigerant flowingrightward in the portions 6, 7 and directing the refrigerant towardU-shaped flat tubular portions 5, while the refrigerant dividing wall 14is formed in the vicinity of the rear header portion 7. The refrigerantinlet pipe 10 extends through the rear header partitioning intermediateplate 3A and has a left end opening which is positioned within the leftend portion 7a of the rear header portion 7. The inner pipe portion 10aof the refrigerant inlet pipe 10 extends through an intermediate portion7b and the right end portion 7c of the rear header portion 7, with arefrigerant passing clearance formed in each refrigerant aperture 25around the pipe portion 10a.

The evaporator 1 can be prepared by collectively brazing the componentsincluding the reinforcing plates 15 provided between each endintermediate plate 2 and the standard intermediate plate 3 adjacentthereto. The presence of the reinforcing plates 15 gives an improvedstrength to the evaporator 1 against the internal pressure thereof,making it possible to reduce the wall thickness of the side plates 8 andthe inner fin members 29.

The evaporator 1 thus constructed has in its interior three paths asshown in FIGS. 2 and 3: a first path 16 extending from the left endportion 7a of the rear head portion 7 through U-shaped flat tubularportions 5a in communication with the portion 7a to the left end portion6a of the front header portion 6, an intermediate path 17 extending froman intermediate portion 6b of the front header portion 6 throughU-shaped flat tubular portions 5b in communication with the portion 6bto the intermediate portion 7b of the rear header portion 7, and a finalpath 18 extending from the right end portion 7c of the rear headerportion 7 through U-shaped flat tubular portions 5c in communicationwith the portion 7c to the right end portion 6c of the front headerportion 6. These paths provide a zigzag refrigerant channel 16, 17, 18.

The presence of the refrigerant dividing wall 14 separates the finalpath 18 into a first branch portion 18a and a second branch portion 18b,the first branch portion 18a extending from flat tubular portions c inthe left portion (upstream portion) of the final path 18 to the leftportion (upstream portion) of front header 6c of the final path 18, thesecond branch portion 18b extending from U-shaped flat tubular portions5c in the right portion (downstream portion) of the final path 18 to theright portion (downstream portion) of front header portion 6c of thefinal path 18.

Accordingly, the refrigerant flowing into the rear header portion 7c isdivided into a portion flowing through the first branch portion 18a, anda portion flowing through the second branch portion 18b, and theserefrigerant portions join within the front header portion 6c to flow outthrough the outlet pipe 11. When having no refrigerant dividing wall,the evaporator has the problem that an increased quantity of refrigerantflows into flat tubular portion at the right end of the final path,hence a limitation to the improvement of the cooling effect. With theevaporator 1 described, however, the refrigerant dividedly flows intothe left part and the right part of the rear header portion 7c of thefinal path 18 and then flows into the individual flat tubular portions5c. This increases the quantity of refrigerant flowing into the flattubular portions 5c at the left of the final path 18, consequentlygiving a uniform distribution of low refrigerant temperatures throughoutthe evaporator.

When the evaporator 1 is to be used in a motor vehicle air conditioner,the air passing through the right half of the evaporator is sent, forexample, toward the driver's seat, and the air passing through the lefthalf thereof toward the passenger's seat. The temperature of the air tobe sent out is approximately equal at left and right even in this case,obviating the likelihood that for example, the passenger's seat will becooled to excess, with the driver's seat cooled insufficiently, namely,the likelihood of imbalance occurring between opposite sides of themotor vehicle.

Although the embodiment described has one refrigerant dividing wallforming intermediate plate 3C, at least two plates of this type may beused. The refrigerant dividing wall 14 has two refrigerant apertures 31,whereas this is not limitative. FIG. 10 shows another preferredembodiment of refrigerant dividing wall forming intermediate plate 3C.The plate 3C shown in the drawing has two refrigerant apertures 31formed at each of the front and rear sides of the through hole 30 in thefront header forming recessed portion 23. The refrigerant apertures 31are arranged at the front and rear sides symmetrically with respect to avertical axis. The refrigerant apertures 31 are preferably up to six innumber. It is desired that the apertures be in one to three pairs, witheach pair arranged symmetrically with respect to a vertical axis.Further the refrigerant apertures 31 are preferably 2.5 to 4.0 mm, morepreferably 3.0 to 3.5 mm, in diameter. The path provided with therefrigerant dividing wall 14 is not limited to the final path 18; thewall may be provided in the path immediately preceding the final path orin each of these paths. Briefly stated, the refrigerant dividing wallcan be modified variously in construction insofar as the wall partlyblocks the refrigerant in one path and partly deflects the refrigeranttoward flat tubular portions to thereby increase the quantity ofrefrigerant to be passed through the flat tubular portions in theupstream portion of that path.

Although the partitions 13, 12 are provided respectively in the frontand rear header portions 6, 7, one in each header portion, twopartitions can be provided in each of the front and rear header portions6, 7 to provide five paths.

The refrigerant inlet pipe 10 has the inner pipe portion 10a accordingto the foregoing embodiment, whereas the inner pipe portion can beomitted. In this case, the refrigerant inlet pipe is connected to theleft end of the rear header portion 7, and the through holes 30 in therear header partitioning plate 3A and the refrigerant dividing wallforming plate 3C for inserting the inner pipe portion 10a are closed.

Although the present invention is applied to an evaporator of thevertical type wherein flat tubular portions are arranged side by side aspositioned vertically according to the foregoing embodiment, theinvention is similarly applicable also to an evaporator of thehorizontal type wherein flat tubular portions are arranged in parallelas positioned horizontally. The front, rear and the left, right in theabove embodiment are determined for the sake of convenience; thefront-rear or the left-right relationship can of course be reversed.

The type of evaporator is not limited to the single-tank layeredevaporator but the invention is useful for evaporators which comprise apair of header portions 7, 6 arranged in parallel, and flat tubularportions 5 arranged side by side and each connected at its opposite endsto the header portions 7, 6, the header portions 7, 6 being providedwith respective partitions 12, 13 for blocking the refrigerant flowingthrough the portions 7, 6 and directing the refrigerant toward flattubular portions 5 to thereby form a refrigerant channel comprising afirst path 16, at least one intermediate path 17 and a final path 18. Atleast one of the header portions 7, 6 is then provided with arefrigerant dividing wall 14 having refrigerant apertures 31 for passingtherethrough a portion of the refrigerant flowing from the upstream path16, 17 into the downstream path 17, 18 while blocking the remainingportion of the refrigerant for deflection toward flat tubular portions5c. As compared with an evaporator having no refrigerant dividing wall,an increased amount of refrigerant then flows into the flat tubularportions in the upstream portion of the final path. The evaporator thusadapted has a uniform distribution of refrigerant temperatures in itsentirety to exhibit an improved cooling capacity.

When the invention is to be applied, for example, to a two-tank layeredevaporators, an upper header portion is provided by the rear headerportion 7 of the above embodiment, and a lower header portion by thefront header portion 6 of the embodiment, whereby an evaporator isreadily available which has the same advantage as described above.

What is claimed is:
 1. An evaporator comprising first and second headerportions arranged in parallel, and flat tubular portions arranged inparallel and each connected at opposite ends thereof to the headerportions, each of the header portions being provided with a partitionfor blocking a refrigerant flowing inside thereof and directing therefrigerant toward some of the flat tubular portions to thereby form arefrigerant channel comprising a first path, at least one intermediatepath and a final path, the evaporator being characterized in that arefrigerant inlet pipe has an inner pipe portion inside the headerportion and the header portion, having the inner pipe portion, isprovided with at least one refrigerant dividing wall having at least onerefrigerant aperture for passing therethrough a portion of therefrigerant flowing from one of the paths into the path downstream fromsaid one path, with the remaining portion of the refrigerant blocked bythe wall and directed toward some of the flat tubular portions.
 2. Anevaporator according to claim 1 wherein the final path causes therefrigerant to turn at a closed end of the first header portion and toflow out of an end of the second header portion which end has arefrigerant outlet, and the refrigerant dividing wall is singly providedin the first header portion of the final path.
 3. An evaporatoraccording to claim 2 wherein a refrigerant inlet pipe has an inner pipeportion inside the header portion.
 4. An evaporator according to claim 1wherein one to six refrigerant apertures are formed.
 5. An evaporatoraccording to claim 4 wherein the refrigerant apertures are arranged in aplurality of pairs, and each pair of refrigerant apertures arepositioned symmetrically.
 6. An evaporator according to claim 5 whereinthe refrigerant apertures are circular and have a diameter of 2.5 to 4.0mm.
 7. An evaporator according to claim 6 wherein the diameter of therefrigerant apertures is 3.0 to 3.5 mm.
 8. An evaporator according toclaim 1, wherein the evaporator has a plurality of plates including atleast one refrigerant dividing wall forming intermediate plate, and therefrigerant dividing wall forming intermediate plate has a flat tubeforming recessed portion and front and rear header forming recessedportions, the header forming recessed portion of the header portionhaving the inner pipe portion formed in its bottom wall with a throughhole having a diameter equal to the outside diameter of the inner pipeportion of the refrigerant inlet pipe.